Shape Memory Alloy Actuators for Projectile Guidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current actuation technologies for gun-fired projectiles and mortars face limitations such as limited control authority, high electrical energy requirements, large volume occupation, and reliability issues under high-g firing accelerations, making them unsuitable for precision guidance and control.
Innovation Solution
The development of actuator stacks with detonation charges and minimal electrical power requirements, integrated into the projectile structure to provide thrust in longitudinal, radial, or rotational directions, utilizing momentum exchange and detonation-based impulsive actuation for high dynamic response and precision control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If electric motors are used for actuation in guided weaponry, then control authority is provided, but volume occupation and electrical energy requirements increase significantly
Solution Approach 1:
The patent replaces electric motors with a purely mechanical actuation system using shape memory alloy (SMA) wires. The SMA wires directly generate mechanical force through thermal actuation, eliminating the need for electric motors, batteries, and power electronics. This substitution dramatically reduces the volume of actuation components while maintaining control authority through the direct mechanical action of the SMA wires on the control surfaces.
Solution Approach 2:
The patent utilizes the phase transition properties of shape memory alloys, changing their physical state between austenite (high temperature, high strength) and martensite (low temperature, low strength) phases. By controlling the temperature of the SMA wires through resistive heating or environmental temperature changes, the actuator can generate large forces and deformations without requiring complex mechanical or electrical systems, thus reducing volume while maintaining control capability.
2Ease of operation
If electric motors and batteries are used for actuation, then actuation function is achieved, but the device becomes expensive and complicated
Solution Approach 1:
The patent eliminates complex electrical systems (motors, batteries, power electronics, wiring) by using shape memory alloy wires that provide actuation through thermal-mechanical coupling. The control system is simplified to basic temperature control or direct electrical resistance heating of the SMA wires, dramatically reducing system complexity and cost while maintaining the actuation function.
Solution Approach 2:
The shape memory alloy wires can utilize environmental temperature changes or aerodynamic heating during flight to activate, reducing or eliminating the need for onboard power sources. The SMA material inherently provides both the actuation force and the structural coupling to the control surfaces, eliminating the need for separate mechanical linkages and mounting hardware.
3Ease of operation
If conventional actuators are used in gun-fired projectiles, then actuation is provided, but reliability under high-g firing accelerations decreases
Solution Approach 1:
The patent replaces electric motors with shape memory alloy wire actuators that are inherently more resistant to high-g accelerations. The SMA wires are flexible, have no moving parts, and can withstand extreme mechanical shocks and vibrations without failure. The wires are directly coupled to the control surfaces through mechanical anchoring, providing reliable actuation even under the high-g firing conditions of gun-launched projectiles.
Solution Approach 2:
The patent incorporates vibration isolation and shock protection measures in the anchoring and mounting of the SMA wires to the projectile structure. The flexible nature of the SMA wires themselves provides inherent shock absorption, and the system is designed to accommodate thermal expansion and mechanical stresses that occur during firing and flight, ensuring reliability under extreme conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These actuators offer high control authority, reduced power needs, increased reliability, and compact design, enabling precise guidance and control of gun-fired projectiles and mortars with enhanced survivability and extended shelf life, while eliminating the need for onboard batteries.
Implementation Method 1
Each actuator stack can include a detonation charge, a primer for igniting the detonation charge and detonation wiring for powering the primer
Data Source
AI summary
Projectiles are provided having a shell and; one or more actuators for providing thrust disposed inside of a wall of the shell; one or more ring portions forming at least a portion of the shell, the one or more ring portions having one or more actuators formed therein for providing thrust and/or one or more actuator stacks for providing thrust, the one or more actuator stacks each having two or more individual actuators for providing thrust.